MULTAN, Pakistan (AP) -- Hundreds of followers and relatives of Pakistan's most feared Islamic militant leader attended his burial on Thursday, a day after he was gunned down in an assault on a police convoy.

Many among the mourners were members of Malik Ishaq's militant Lashkar-e-Jhangvi group and chanted anti-government slogans calling for revenge. The funeral in Ishaq's hometown of Rahim Yar Khan in central Pakistan was held under tight security, according to police officer Ashfaq Gujjar.

Ishaq's Lashkar-e-Jhangvi group has links to the Taliban and to al-Qaida, and allegedly masterminded the killing of scores of minority Shiites across Pakistan.

He was killed with 13 other militants, including his two sons, in the Wednesday assault on the convoy, when he was officially in police custody.

No one claimed responsibility for the attack but Pakistani police have been accused of extrajudicial slayings in the past. Ishaq's nephew Mohammad Kashif alleged that the attack was a staged shootout, and blamed the authorities for it.

But provincial minister, Shuja Khanzada, described Ishaq as a "symbol of terror" and said he was behind many acts of terrorism in Pakistan but he had been freed by courts in the past due to lack of evidence.

Ishaq was so feared in Pakistan that frightened judges hid their faces from him and even offered him tea and cookies in court.

Arrested in 1997, Ishaq remained in prison for about 14 years but could not be convicted in any of over 200 cases, including the killings of 70 Shiites.

He walked out of prison in 2011 after a behind-the-scene deal to help the government influence other militants to denounce violence. But he repeatedly violated the deal by urging in public for killings of Shiites and helping coordinate several top militant attacks.

He was believed to be in his mid-50s and had operated freely for years in Pakistan as its intelligence services helped nurture Islamic militant groups in the 1980s and 1990s to maintain influence in Afghanistan and counter archrival India.

However, Ishaq proved his usefulness to the army in 2009, when he was flown from jail to negotiate with militants who had stormed part of the military headquarters in Rawalpindi and were holding hostages.

He was one of the three founders of Laskhar-e-Jhangvi in the early 1990s. The group later allied itself with al-Qaida and the Taliban. The U.S. State Department designated Ishaq as a terrorist in February 2014, ordering any U.S. assets he held frozen.

He was arrested again eight months ago on charges of making public speeches inciting sectarian violence.

Then, last week, police took him to a counter terrorism center to investigate his alleged involvement in the killings of two Shiites. Wednesday's attack on the convoy happened as he was being taken to a place where the information he provided later helped police locate a weapons cache.

On Thursday, militants attacked a police station in the eastern Pakistani city of Gujrat. Police officer Rai Zameer said two of the attackers were killed and others fled. In another incident, police killed seven militants in a raid in the southern port city of Karachi.

Also, police detained a close aide of Ishaq and nearly 15 activists from his group in the southwestern city of Quetta on Thursday.